S
M
T
W
T
F
S
30
76°
52°
31
75°
51°
1
75°
53°
2
77°
56°
3
75°
52°
4
77°
52°
5
77°
50°
6
76°
51°
7
75°
48°
8
76°
49°
9
74°
56°
10
74°
49°
11
73°
48°
12
74°
49°
13
75°
54°
14
78°
50°
15
78°
54°
16
80°
54°
17
80°
53°
18
79°
53°
19
79°
52°
20
78°
45°
21
70°
50°
22
70°
52°
23
74°
51°
24
76°
52°
25
77°
48°
26
75°
42°
27
71°
43°
28
66°
44°
29
65°
44°
30
65°
42°
1
Hist. Avg.
73°
47°
2
Hist. Avg.
72°
46°
3
Hist. Avg.
72°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Princeton
Princeton's September 2026 forecast shows daily high temperatures ranging from 65° to 80°, with overnight lows between 42° and 56°. The average high for September is 75° with an average low of 50°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Princeton. See also: October | November | December.
